My 88 vert has 35k miles on it and runs great ... but has that typical lag around 3200-3400rpm before the six ports open up (at least, thats my impression). Its been a long time (few years) since I had another RX7 with this issue so I've forgotten what the fix is. Is there any consensus today on the things to look for to try to solve that issue? grounding? cleaning something up, etc?

 

Try turning the actuators by hand and see if they are sticking. If they are take em out and give them a good cleaning. Aaron Cake has some good info on his site about cleaning them too.

 

Ok so lets assume they're working physically -- I can definitely feel them engage -- but before they engage there's a serious lag or feeling of loss of power for a few hundred RPM.

(i will check them though when I get home)

 

Exhaust pressure makes them work.

Remove the air line to the actuators and lay it to where it will not get burnt up. Go for a ride. IF you feel the same *lag* as before, it is not the actuators, it's the secondarys coming online.

 

The secondaries ... you mean fuel injectors?

 

Yes, the injector transition point is unfortunately set to the same RPM as the 6 port activation.

 

So if the valves open slowly, you lag due to fuel starvation? I assume this isn't fixable?

 

are you running stock exhaust system?

not sure what air line hailers is talking about since s4 doesn't run on vacum, but just pop the hood and rev the engine you should see both actuators move at the 3800 rpm range
I have an s4 and despite popular belief they WILL move with no load on the engine, this is again because the s4 works on exhaust pressure not vacum like the s5

there are two 10MM bolts holding each on there, the front one will be easier to get off w/out air pump in the way
then the actuator will slide off the rod, pull it straight towards the tire, may have to pry at it a little, clean the gasket areas and soak that sucker in some PB blaster or something like it, through some high temp sealer on there, being sure not to clog the holes, and go for a ride see if it works

well not really sure about soaking it, don't know whats inside of that thing, may or may not hurt something, but you can find them all over the forum, just make sure you get s4
I have not seen s5 but think they have a vac tube on them

 

Good to know ... when the weather gets a bit cooler I'll pop it all open and look at it. I'm continually surprised at the differences between the S4 and S5's.

(im not-so-secretly hoping my motor will blow up so I have an excuse to swap in a TII motor... that would make this car perfect.)

 

S4 NAs use exhaust backpressure to open the actuators.

S5 NAs use air pressure (not vacuum) from the air pump to open the actuators.

If your actuators are sticking, it could add to the roughness, but it's more likely related to the injector transition. Cleaning of the ECU ground will sometimes help to (under the intake manifold) smooth out the transition & get rid of the stumble.

 

actually im pretty sure the s5 actuators do open with vacuum.

 

No, they don't. Maybe you guys are just confused because the actuator rods actually move IN on S5s. But it's because the diaphrams are different, not because vacuum is applied.

From the S5 FSM:

 

Well I stand corrected, that clearly says apply compressed air...

so there you have it, they both work on air pressure not vacum, just the S4 comes from backpressure and s5 comes from air pump via solenoid valve

 

Yes, the secondary fuel injectors is what I meant.

When I say AIR line, I mean the exhaust air pressure that is fed to the actuators by a exhaust air line from the split air pipe. The pipe that gets fed is on the rear side of the manifold. I used AIR instead of VACCUMM for a purpose.

If you'll just simply open the hood, reach down and pull the air line off the actuators feed line and set it aside where it won't get burnt up by the exhaust, you should now be able to just get in the car and drive it. Drive it as you were before and see if there is still the stumble/hesitation/trait you saw before.

If the problem still exists, then the problem does not lie with the aux actuators.

Leaving the hose/air line off the actuators feed line will harm nothing at all even if you don't plug the lines.